Add Kotlin multiplatform support

.github/labeler.yml

@@ -48,6 +48,7 @@ java:
 kotlin:
   - '**/*.kt'
   - src/idl_gen_kotlin.cpp
+  - src/idl_gen_kotlin_kmp.cpp
 
 lua:
   - '**/*.lua'

.github/workflows/build.yml

@@ -422,9 +422,14 @@ jobs:
       with:
         distribution: 'temurin'
         java-version: '11'
+    - name: Build flatc
+      run: |
+       cmake -DFLATBUFFERS_BUILD_TESTS=OFF -DFLATBUFFERS_BUILD_FLATLIB=OFF -DFLATBUFFERS_BUILD_FLATHASH=OFF .
+       make -j
+       echo "${PWD}" >> $GITHUB_PATH
     - name: Build
       working-directory: kotlin
-      run: ./gradlew clean iosX64Test macosX64Test
+      run: ./gradlew clean iosSimulatorArm64Test macosX64Test macosArm64Test
 
   build-kotlin-linux:
     name: Build Kotlin Linux
@@ -437,6 +442,11 @@ jobs:
         distribution: 'temurin'
         java-version: '11'
     - uses: gradle/wrapper-validation-action@v1.0.5
+    - name: Build flatc
+      run: |
+       cmake -DFLATBUFFERS_BUILD_TESTS=OFF -DFLATBUFFERS_BUILD_FLATLIB=OFF -DFLATBUFFERS_BUILD_FLATHASH=OFF .
+       make -j
+       echo "${PWD}" >> $GITHUB_PATH
     - name: Build
       working-directory: kotlin
       # we are using docker's version of gradle

.gitignore

@@ -151,3 +151,5 @@ flatbuffers.pc
 # https://cmake.org/cmake/help/latest/module/FetchContent.html#variable:FETCHCONTENT_BASE_DIR
 cmake-build-debug/
 _deps/
+**/.gradle/**
+kotlin/**/generated

CMakeLists.txt

@@ -160,6 +160,7 @@ set(FlatBuffers_Compiler_SRCS
   src/idl_gen_csharp.cpp
   src/idl_gen_dart.cpp
   src/idl_gen_kotlin.cpp
+  src/idl_gen_kotlin_kmp.cpp
   src/idl_gen_go.cpp
   src/idl_gen_java.cpp
   src/idl_gen_ts.cpp

android/.project

@@ -10,7 +10,7 @@
 	</natures>
 	<filteredResources>
 		<filter>
-			<id>1677235311958</id>
+			<id>1672434305228</id>
 			<name></name>
 			<type>30</type>
 			<matcher>

include/flatbuffers/idl.h

@@ -342,7 +342,10 @@ struct FieldDef : public Definition {
   bool Deserialize(Parser &parser, const reflection::Field *field);
 
   bool IsScalarOptional() const {
-    return IsScalar(value.type.base_type) && IsOptional();
+    return IsScalar() && IsOptional();
+  }
+  bool IsScalar() const {
+      return ::flatbuffers::IsScalar(value.type.base_type);
   }
   bool IsOptional() const { return presence == kOptional; }
   bool IsRequired() const { return presence == kRequired; }
@@ -725,6 +728,7 @@ struct IDLOptions {
     kSwift = 1 << 16,
     kNim = 1 << 17,
     kProto = 1 << 18,
+    kKotlinKmp = 1 << 19,
     kMAX
   };
 

kotlin/benchmark/build.gradle.kts

@@ -1,5 +1,3 @@
-import org.jetbrains.kotlin.ir.backend.js.compile
-
 plugins {
   kotlin("multiplatform")
   id("org.jetbrains.kotlinx.benchmark")
@@ -27,7 +25,7 @@ benchmark {
       iterationTime = 300
       iterationTimeUnit = "ms"
       // uncomment for benchmarking JSON op only
-      include(".*JsonBenchmark.*")
+       include(".*FlatbufferBenchmark.*")
     }
   }
   targets {
@@ -36,24 +34,34 @@ benchmark {
 }
 
 kotlin {
-  jvm()
-
-  sourceSets {
-
-    all {
-      languageSettings.enableLanguageFeature("InlineClasses")
+  jvm {
+    compilations {
+      val main by getting { }
+      // custom benchmark compilation
+      val benchmarks by compilations.creating {
+        defaultSourceSet {
+          dependencies {
+            // Compile against the main compilation's compile classpath and outputs:
+            implementation(main.compileDependencyFiles + main.output.classesDirs)
+          }
+        }
+      }
     }
+  }
 
+  sourceSets {
     val jvmMain by getting {
       dependencies {
         implementation(kotlin("stdlib-common"))
         implementation(project(":flatbuffers-kotlin"))
         implementation(libs.kotlinx.benchmark.runtime)
-        implementation("com.google.flatbuffers:flatbuffers-java:2.0.3")
+        implementation("com.google.flatbuffers:flatbuffers-java:23.5.9")
         // json serializers
         implementation(libs.moshi.kotlin)
         implementation(libs.gson)
       }
+      kotlin.srcDir("src/jvmMain/generated/kotlin/")
+      kotlin.srcDir("src/jvmMain/generated/java/")
     }
   }
 }
@@ -67,3 +75,64 @@ tasks.register<de.undercouch.gradle.tasks.download.Download>("downloadMultipleFi
   dest(File("${project.projectDir.absolutePath}/src/jvmMain/resources"))
   overwrite(false)
 }
+
+abstract class GenerateFBTestClasses : DefaultTask() {
+  @get:InputFiles
+  abstract val inputFiles: ConfigurableFileCollection
+
+  @get:Input
+  abstract val includeFolder: Property<String>
+
+  @get:Input
+  abstract val outputFolder: Property<String>
+
+  @get:Input
+  abstract val variants: ListProperty<String>
+
+  @Inject
+  protected open fun getExecActionFactory(): org.gradle.process.internal.ExecActionFactory? {
+    throw UnsupportedOperationException()
+  }
+
+  init {
+    includeFolder.set("")
+  }
+
+  @TaskAction
+  fun compile() {
+    val execAction = getExecActionFactory()!!.newExecAction()
+    val sources = inputFiles.asPath.split(":")
+    val langs = variants.get().map { "--$it" }
+    val args = mutableListOf("flatc","-o", outputFolder.get(), *langs.toTypedArray())
+    if (includeFolder.get().isNotEmpty()) {
+      args.add("-I")
+      args.add(includeFolder.get())
+    }
+    args.addAll(sources)
+    println(args)
+    execAction.commandLine = args
+    print(execAction.execute())
+  }
+}
+
+// Use the default greeting
+tasks.register<GenerateFBTestClasses>("generateFBTestClassesKt") {
+  inputFiles.setFrom("$projectDir/monster_test_kotlin.fbs")
+  includeFolder.set("$rootDir/../tests/include_test")
+  outputFolder.set("${projectDir}/src/jvmMain/generated/kotlin/")
+  variants.addAll("kotlin-kmp")
+}
+
+tasks.register<GenerateFBTestClasses>("generateFBTestClassesJava") {
+  inputFiles.setFrom("$projectDir/monster_test_java.fbs")
+  includeFolder.set("$rootDir/../tests/include_test")
+  outputFolder.set("${projectDir}/src/jvmMain/generated/java/")
+  variants.addAll("kotlin")
+}
+
+project.tasks.forEach {
+  if (it.name.contains("compileKotlin")) {
+    it.dependsOn("generateFBTestClassesKt")
+    it.dependsOn("generateFBTestClassesJava")
+  }
+}

kotlin/benchmark/monster_test_java.fbs

@@ -0,0 +1,37 @@
+// Example IDL file for our monster's schema.
+
+namespace jmonster;
+
+enum JColor:byte { Red = 0, Green, Blue = 2 }
+
+union JEquipment { JWeapon } // Optionally add more tables.
+
+struct JVec3 {
+  x:float;
+  y:float;
+  z:float;
+}
+
+table JMonster {
+  pos:JVec3;
+  mana:short = 150;
+  hp:short = 100;
+  name:string;
+  friendly:bool = false (deprecated);
+  inventory:[ubyte];
+  color:JColor = Blue;
+  weapons:[JWeapon];
+  equipped:JEquipment;
+  path:[JVec3];
+}
+
+table JWeapon {
+  name:string;
+  damage:short;
+}
+
+table JAllMonsters {
+   monsters: [JMonster];
+}
+
+root_type JAllMonsters;

kotlin/benchmark/monster_test_kotlin.fbs

@@ -0,0 +1,37 @@
+// Example IDL file for our monster's schema.
+
+namespace monster;
+
+enum Color:byte { Red = 0, Green, Blue = 2 }
+
+union Equipment { Weapon } // Optionally add more tables.
+
+struct Vec3 {
+  x:float;
+  y:float;
+  z:float;
+}
+
+table Monster {
+  pos:Vec3;
+  mana:short = 150;
+  hp:short = 100;
+  name:string;
+  friendly:bool = false (deprecated);
+  inventory:[ubyte];
+  color:Color = Blue;
+  weapons:[Weapon];
+  equipped:Equipment;
+  path:[Vec3];
+}
+
+table Weapon {
+  name:string;
+  damage:short;
+}
+
+table AllMonsters {
+   monsters: [Monster];
+}
+
+root_type AllMonsters;

kotlin/benchmark/src/jvmMain/kotlin/com/google/flatbuffers/kotlin/benchmark/FlatbufferBenchmark.kt

@@ -0,0 +1,68 @@
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
+package com.google.flatbuffers.kotlin.benchmark
+
+
+import com.google.flatbuffers.kotlin.FlatBufferBuilder
+import jmonster.JAllMonsters
+import jmonster.JMonster
+import jmonster.JVec3
+import monster.AllMonsters.Companion.createAllMonsters
+import monster.AllMonsters.Companion.createMonstersVector
+import monster.Monster
+import monster.Monster.Companion.createInventoryVector
+import monster.MonsterOffsetArray
+import monster.Vec3
+import org.openjdk.jmh.annotations.*
+import java.util.concurrent.TimeUnit
+
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Measurement(iterations = 20, time = 1, timeUnit = TimeUnit.NANOSECONDS)
+open class FlatbufferBenchmark {
+
+  val repetition = 1000000
+  val fbKotlin = FlatBufferBuilder(1024 * repetition)
+  val fbJava = com.google.flatbuffers.FlatBufferBuilder(1024 * repetition)
+
+  @OptIn(ExperimentalUnsignedTypes::class)
+  @Benchmark
+  fun monstersKotlin() {
+    fbKotlin.clear()
+    val monsterName = fbKotlin.createString("MonsterName");
+    val items = ubyteArrayOf(0u, 1u, 2u, 3u, 4u)
+    val inv = createInventoryVector(fbKotlin, items)
+    val monsterOffsets: MonsterOffsetArray = MonsterOffsetArray(repetition) {
+      Monster.startMonster(fbKotlin)
+      Monster.addName(fbKotlin, monsterName)
+      Monster.addPos(fbKotlin, Vec3.createVec3(fbKotlin, 1.0f, 2.0f, 3.0f))
+      Monster.addHp(fbKotlin, 80)
+      Monster.addMana(fbKotlin, 150)
+      Monster.addInventory(fbKotlin, inv)
+      Monster.endMonster(fbKotlin)
+    }
+    val monsters = createMonstersVector(fbKotlin, monsterOffsets)
+    val allMonsters = createAllMonsters(fbKotlin, monsters)
+    fbKotlin.finish(allMonsters)
+  }
+
+  @Benchmark
+  fun monstersjava() {
+    fbJava.clear()
+    val monsterName = fbJava.createString("MonsterName");
+    val inv = JMonster.createInventoryVector(fbJava, byteArrayOf(0, 1, 2, 3, 4).asUByteArray())
+    val monsters = JAllMonsters.createMonstersVector(fbJava, IntArray(repetition) {
+      JMonster.startJMonster(fbJava)
+      JMonster.addName(fbJava, monsterName)
+      JMonster.addPos(fbJava, JVec3.createJVec3(fbJava, 1.0f, 2.0f, 3.0f))
+      JMonster.addHp(fbJava, 80)
+      JMonster.addMana(fbJava, 150)
+      JMonster.addInventory(fbJava, inv)
+      JMonster.endJMonster(fbJava)
+    })
+    val allMonsters = JAllMonsters.createJAllMonsters(fbJava, monsters)
+    fbJava.finish(allMonsters)
+  }
+
+}

kotlin/benchmark/src/jvmMain/kotlin/com/google/flatbuffers/kotlin/benchmark/FlexBuffersBenchmark.kt

@@ -13,6 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+@file:OptIn(ExperimentalUnsignedTypes::class)
+
 package com.google.flatbuffers.kotlin.benchmark
 import com.google.flatbuffers.ArrayReadWriteBuf
 import com.google.flatbuffers.FlexBuffers

kotlin/benchmark/src/jvmMain/kotlin/com/google/flatbuffers/kotlin/benchmark/JsonBenchmark.kt

@@ -53,9 +53,10 @@ open class JsonBenchmark {
 
   val fbParser = JSONParser()
 
-  final val twitterData = this.javaClass.classLoader.getResourceAsStream("twitter.json")!!.readBytes()
-  final val canadaData = this.javaClass.classLoader.getResourceAsStream("canada.json")!!.readBytes()
-  final val citmData = this.javaClass.classLoader.getResourceAsStream("citm_catalog.json")!!.readBytes()
+  final val classLoader = this.javaClass.classLoader
+  final val twitterData = classLoader.getResourceAsStream("twitter.json")!!.readBytes()
+  final val canadaData = classLoader.getResourceAsStream("canada.json")!!.readBytes()
+  final val citmData = classLoader.getResourceAsStream("citm_catalog.json")!!.readBytes()
 
   val fbCitmRef = JSONParser().parse(ArrayReadBuffer(citmData))
   val moshiCitmRef = moshi.adapter(Map::class.java).fromJson(citmData.decodeToString())

kotlin/benchmark/src/jvmMain/kotlin/com/google/flatbuffers/kotlin/benchmark/UTF8Benchmark.kt

@@ -35,14 +35,14 @@ import kotlin.random.Random
 @BenchmarkMode(Mode.AverageTime)
 @OutputTimeUnit(TimeUnit.MICROSECONDS)
 @Measurement(iterations = 100, time = 1, timeUnit = TimeUnit.MICROSECONDS)
-class UTF8Benchmark {
-
-  private final val sampleSize = 5000
-  private final val stringSize = 25
-  final var sampleSmallUtf8 = (0..sampleSize).map { populateUTF8(stringSize) }.toList()
-  final var sampleSmallUtf8Decoded = sampleSmallUtf8.map { it.encodeToByteArray() }.toList()
-  final var sampleSmallAscii = (0..sampleSize).map { populateAscii(stringSize) }.toList()
-  final var sampleSmallAsciiDecoded = sampleSmallAscii.map { it.encodeToByteArray() }.toList()
+open class UTF8Benchmark {
+
+  private val sampleSize = 5000
+  private val stringSize = 25
+  private var sampleSmallUtf8 = (0..sampleSize).map { populateUTF8(stringSize) }.toList()
+  private var sampleSmallUtf8Decoded = sampleSmallUtf8.map { it.encodeToByteArray() }.toList()
+  private var sampleSmallAscii = (0..sampleSize).map { populateAscii(stringSize) }.toList()
+  private var sampleSmallAsciiDecoded = sampleSmallAscii.map { it.encodeToByteArray() }.toList()
 
   @Setup
   fun setUp() {